Calculating Initial Speed from 2D Kinematics Problem

[brushman]

Homework Statement

A stone thrown horizontally from a height of 6.02m hits the ground at a distance of 13.90m. Calculate the initial speed of the stone. Neglect air resistance.

Homework Equations

1. v = v0 + at
2. x = x0 + (1/2)(v0+v)t
3. x = x0 + v0t + (1/2)at^2
4. v^2 = v0^2 + 2a(x-x0)

The Attempt at a Solution

First I solved for t using the y components of equation 3. So
0 = x0y + (1/2)at^2;
a = -g;
x0y = 6.02;

so t = 1.23s

Then using x components of equation 2 I said
v0x = vx;
13.9 = v(1.23);
so v = 11.3 m/s

but that's not the right answer.

Sorry this isn't more clear, I'm in a hurry. Thanks.

 

[collinsmark]

First I solved for t using the y components of equation 3. So
0 = x0y + (1/2)at^2;
a = -g;
x0y = 6.02;

so t = 1.23s

I don't think this part is right. Double check your calculations. (And don't forget to take the square root before arriving at your final value for t. )

 

[brushman]

omg, I swear I went over this problem 100 times and didn't catch that. Thanks.